06 yzf450 Help cant Figure it out.

So my customer brought in an 06yzf450. It acts like its running really lean. Backfiring, popping, shooting flames. With a minute or less its hot. I changed the gas. Changed the jetting. Adjusted the valves. Correct timming. Checked for an air leak. I can not figure it out. Nothing seemed to help. He does not want me to pull the head due to money. There is a rattle you can hear from time to time you can when kicking it over. So im sure its about to go. Any ideas or suggestions would be helpful.

Is the plate in the carb slide in upside down?

Nope its in right.

Checked and adjusted hot start and enrichner.

Not to second guess but I would check the valve clearence again. Just sounds like the symptoms. Have you checked out the exhaust packing?

Have you checked to make sure that the idle circuit is working properly? Have you cleaned or replaced the pilot jet?

Checked and adjusted hot start and enrichner.

Replace the o ring gasket on the slide plate and make sure the plate intself isn't cracked. Use a magnifying glass and make sure! I have fixed several yz's that have had the same problem, and also make sure the acc pump nozzle is squirting fuel!

Edited by CROGGR

open her up she might want a rebuild

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